How to Remove and Replace a Small Concrete Entry Pad

A sagging, cracked concrete pad at an entry-way says anything but welcome. And it can go from eyesore to disaster if it slopes toward your home’s foundation and directs rainwater right into your nicely finished basement! If your old pad needs replacing, you’ll be happy to know it’s a fairly easy task. In fact, you can replace one in a single day. Here are some tips for building a new home for your welcome mat.

Step 1: Start with a sledgehammer

Start with a sledgehammer

A 10-lb. sledgehammer is usually all you need to bust up that nasty old pad (and get a good workout in the process). To protect the house from flying chips, cover any nearby glass with a sheet of 1/2-in. plywood (shown at left). And be sure to wear goggles to protect your eyes.

A few swings with a sledgehammer
will let you know
right away if you need to call
in some heavier equipment. A
rental jackhammer will break
up a slab much faster than a
sledgehammer, with fewer
blisters and less sweat.
For a small slab, rent an
electric model rather than a
pneumatic hammer. Rental
fees will be about $80 for
24 hours.

Step 2: Build the form

Build the form

Using straight 2x4s, lay out the form’s three sides and screw them
together. Take diagonal measurements to check for square (if they’re
equal, the form is square). Drive stakes—one every 3 ft.—along the outside
of the form, being careful not to bend the 2x4s. Level the 2x4 that runs
parallel to the house and drive screws through the stakes and into the 2x4
to hold it in place. Next, be sure the sides of the form slope away from the
house 1/4 in. for every foot and screw through the stakes to secure them.

Step 3: Pin the pad to the foundation

Pin the pad to the foundation

Using a hammer drill and
masonry bit, drill 1/2-in.
holes 4 in. deep in your
home’s concrete foundation
and space them about a foot
apart. Then, using a
hammer, tap 12-in.-long
pieces of 1/2-in. rebar into
the holes to connect the new
pad to the foundation. The
rebar will ensure that your
new pad maintains its slope
away from the house. Note:
Not all municipalities allow
this practice, so check with
your local building inspector.

Video: How to Pour a Concrete Slab

Step 4: Level the wet concrete

Level the wet concrete

To get a nice, flat surface that’s perfectly
sloped, find a straight 2x4 that’s a foot
longer than the width of the form and set it
on top of the form as you start pouring the
concrete. Use it to level the wet concrete by
pulling it from the house toward you while
working the board side to side—a process
called “screeding.”

The mix should be slightly higher than the
top of the form when you start. Poke the mix
with a shovel to work out any air pockets,
especially near edges and corners. For a
smoother finish on the pad’s edges, tap the
sides of the form with a hammer.

Step 5: Float the concrete

Float the concrete

Start smoothing the concrete—also
called “floating”—with a magnesium
(mag) float. They cost about $25 at
home centers. Do this when the concrete
has started to set up and you can
push your finger into it only about 1/4
in. To float hard-to-reach areas, kneel
on a 2x4 laid across the form (see
Photo 4). Make long, sweeping strokes
in an arc with the leading edge of the
mag float lifted slightly. Try to finish
this step within an hour of starting to
pour the concrete. If it’s hot and dry
outside, you’ll have to work even faster.

Step 6: Round over the edges

Round over the edges

Fifteen to 30 minutes after
screeding, use a steel edging
tool—about $6 at home centers—
to smooth and round
over the edges of the pad. This
gives a nice-looking shape to
the edges and forces the
aggregate away from the
corner. Do this a few times
during floating (see Photo 5)
and after.

Reinforcement Isn't Required, But...

For a small concrete pad—less than 40 sq. ft.—
you don’t normally have to bother installing steel
reinforcing bar (rebar). However, doing so adds
strength and crack resistance to the pad if you
lay out the rebar in a grid pattern 2 ft. on center.

You’ll find 10-ft. lengths of rebar for about $5
each at home centers, and you can cut them to
size with a hacksaw or an angle grinder. You’ll
also need tie wires and a
wire-twisting tool to connect the pieces of
rebar in a grid pattern. Get more information
about reinforcing concrete with rebar.

Step 7: Add texture with a broom

Add texture with a broom

Use a special concrete broom or any stiff-bristle
broom about 15 minutes after floating to add a slip-resistant texture
to the top of the pad. The coarser you want the texture, the earlier
you should broom. The grooves created by the broom should
follow the direction of the slope so water runs off easily. Brooming
also hides imperfections in float work.

Four Things to Know About Concrete

Too much water
weakens concrete: If you mix too much water with
concrete, cement crystals form farther
apart, leaving concrete weak
and porous. That can cause trouble
later as pores and pockets fill with
water, freeze and break up the concrete’s
surface. With the right
amount of water, cement crystals
grow tightly together and interweave
to form strong, watertight
concrete.

Floating too soon
leads to trouble: As concrete sets, water rises to the
surface. Left alone, this “bleed
water” is reabsorbed into the concrete.
But if you float the watery
surface, you’ll force the aggregate
and cement down, leaving a watery
mix of sand and too little cement
on top. Wait for the bleed to disappear
before floating. Also, don’t
overwork it. Too much floating (or
troweling) will lead to a less durable
surface.

The longer it stays
damp, the better: Concrete doesn’t harden because
it’s drying; it hardens because it’s
wet. The longer concrete stays
damp, the harder and stronger it
gets. The hardening or “curing” process
can continue for weeks if the
concrete dries slowly. Covering it
with a sheet of plastic also slows
the curing process.

It can burn your
skin: Some people get concrete on their
skin and don’t have any problems,
but others are more sensitive to it.
Until they cure, all cement-based
products have the potential to
leave minor burns on your skin.
Play it safe and wear a long-sleeved
shirt, long pants, boots and
waterproof gloves when working
with concrete.

Step 8: Cover the pad

Cover the pad

To prevent the concrete from cracking while it’s
curing (hardening), cover it with a plastic sheet to
slow the process. Wetting the pad with a fine spray
of water every two to three hours for the first day
helps too. Higher temperatures require more frequent
wetting. The more time concrete has to cure,
the stronger it will be.

Order the Right Concrete Mix

Bagged concrete
vs. ready-mix:

Most small pads require less than
one yard—27 cu. ft.—of concrete. You
can buy several bags at the home center, which you’ll
have to lug home, mix with water and
pour yourself. It’s a lot of work, but it
might make more sense financially
for a small pad at the bottom of your
deck stairs. For bigger pads, have
“ready-mix” concrete delivered. It
comes mixed with water and the
delivery guy will pour it right into your
forms. Prices vary by region, but
expect to pay about $300 for 1 yard.
Order it a few days ahead. If rain threatens,
you can usually cancel up to two
hours before delivery.

Order the right
concrete mix:

Plan to pour a pad at least 4 in. thick
and calculate the right volume.
Concrete is ordered in cubic yards.
Many suppliers have calculators on
their website, but it’s fairly easy to
figure out how much you need. First
figure out the cubic footage, then convert
to yards by dividing by 27. Here’s
how: Multiply the length of your pad by
the width by the depth (4 in. = . 33 ft.)
and divide the total by 27. Order a little
bit more than you need. A good rule of
thumb is to order an extra 5 percent
rounded up to the next 1/4 yd. to handle
spillage and uneven bases.

Order from the nearest supplier.
Get fresh concrete mixed near the
site, not across town by some company
with a lower price.

Ask for 5 percent “air entrainment”
in the mix. Suppliers add a chemical
that traps microscopic air bubbles to
help the concrete accommodate the
expansion and shrinkage caused by
climatic changes such as freezing.

Get the right strength. Tell the dispatcher
you’re pouring a pad and
they’ll recommend the correct “bag
mix” (ratio of cement to aggregate
and sand). In cold climates, they’ll
probably suggest at least a 3,000-lb.
mix. That means the concrete can
support a 3,000-lb. load per square
inch without failing.

Have your checkbook ready. You’ll
have to pay after the concrete’s
unloaded.

The truck arrives with the concrete
premixed with the correct water content.
But the driver may send a little
concrete down the chute and ask if
you’d like more water added. Unless
the mix is too dry to get down the
chute, forget it. It should be thick—not
runny. Wetter mud may be easier to
place (fill the forms), but the wetter
the mix, the weaker the concrete.